1. Field of the Invention
The present invention is in the field of a flexible reflex-reflective article and method of making the same.
2. The Prior Art
It is known per se to provide reflex-reflective articles, such as highway signs, license plates, highway markings and the like which will retro-reflect light which strikes it at a small angle with respect to the material by embedding in a coating or carrier having reflective flakes or the like a multiplicity of minute glass spheres. By way of example, processes and articles pertaining to retro-reflectivity utilizing spheres are disclosed in one or more of the following U.S. Pat. Nos.:
______________________________________ 2354,018 Heltzer 2354,049 Palmquist 2399,741 Palmquist 2383,884 Palmquist 2555,715 Tatum 2574,971 Heltzer 2963,378 Palmquist 3989,775 Jack 3934,065 Tung 3915,771 Gatzke 3877,787 Buzbee ______________________________________
It is desirable for purposes of safety that the retro-reflective surface be undulant (such term as hereinafter used pertaining to a three dimensional or pattern array, as opposed to a flat surface) since, in view of the narrow angle reflective properties of the spheres, an undulant surface will provide a greater likelihood of haphazard light impinged against the retro-reflective surface being perceived by a viewer than would a flat retro-reflective surface.
The provision of undulant or corrugated reflex-reflective surfaces on materials which will not be flexed or bent in use provides no special problems since it is merely necessary to coat a surface having the desired undulant or corrugated characteristics with a suitable binder and apply a layer of spheres to the surface. However, the provision of a reflex-reflective article, such as a fabric or the like, which has both an undulant surface characteristic for optimum safety and which also is capable of being laundered, flexed, bent twisted and creased without loss of reflex-reflectivity presents special problems. These problems arise since the glass spheres, for permanence of connection, must be embedded into the carrier material to a substantial depth, normally at least equal to and preferably beyond the equator, so that they will not become dislodged in handling.
While it is a simple matter to embed the spheres to a desired depth on a flat surface, there are no known procedures for accurately controlling the embedment of the spheres on an undulant surface.
It has heretofore been suggested, in accordance by way of example, with U.S. Pat. No. 3,989,775, to apply a mono layer of spheres to an embossable plastic material, embed the spheres into the plastic while the same is in a flatwise condition, and thereafter emboss the plastic to a desired pattern to achieve the desired undulant surface whereby light incident at a large angle to the plane of the surface of the material will nonetheless be perceived by a viewer looking at the material in a direction normal to the plane thereof.
The material which is the subject of said patent, however, must be embossable plastic and, thus, cannot have the "hand" or feel of a fabric. Moreover, in order to achieve a desired undulant effect, it is necessary to provide an embossing die specific to each desired characteristic of the material, i.e. if a fine pattern is desired, a fine grain embossing die is needed, etc.
Additionally, an article in accordance with the subject patent does not permit of dry cleaning, washing, wringing or rough handling.